Histopathogenesis Of Root-Knot Nematode, Meloidogyne Incognita And Growth Of Four Banana Cultivars As Affected By Different Inoculation Levels

A.M. Kheir⁽¹⁾A.W. Amin⁽¹⁾H. Hendy⁽²⁾and M.S. Mostafa^(2)
(1) Department of Agriculture Zoology and Nematology, Faculty of Agriculture, Cairo University, Egypt
⁽²⁾Plant Protection Department, Desert Research Institute, Nematology Unit, Cairo, Egypt

Abstract

The influence of four inoculation levels (100, 1,000, 5,000 and 10,000) of Meloidogyne incognita on the nematode behaviour and growth response of four banana cultivars were studied under greenhouse conditions. In general, the nematode final population was proportionally increased with the initial inoculation. On the other hand, the rate of build up of the nematode negatively correlated with its population initials. Comparatively, banana cv Grande-Naine had remarkable final population when inoculated with 100 or 10,000 juveniles of root-knot nematode; while Maghraby sustained high populations with all tested inocula. Contrary, cv Basrai harbored the lowest nematode final population at any of the inoculum levels. Also, the nematode population level was low or moderate on banana cv Williams, when inoculated with the above mentioned inocula. All nematode inoculation levels tested suppressed the plant growth of the four banana cultivars. Regardless of the cultivar, the growth reduction was increased when inoculum level was increased. Histopathological observations of infected banana roots, showed anatomical alterations in root tissues typical to those caused by M. incognita infection. Juveniles penetrate the cortical layers via vascular tissues feeding on cellular contents. Hyperplasia and hypertrophy in stele tissue were noticed in close vicinity to nematode bodies. A cluster of 3-5 of giant cells with thick cell wall and granulated cytoplasm were formed around the anterior region of the nematode. Root damage resulted from break down in stele elements and compactness in cortical layers due to nematode development and giant cells formation was observed.